Field of the Invention
Antistatic and static dissipative films and coatings are important and widely used to prevent harmful buildup of static electricity. Antistatic and static dissipative coatings are known from U.S. Pat. Nos. 4,089,997; 4,278,578; 4,322,331; 4,459,352; 4,556,506; 4,596,668; and 4,642,263. Effective materials that are described in these patents for reducing resistance include polystyrene sulphonic acid, co(ethylene/maleic acid) sodium salt, aliphatic polycarboxylic acid, potassium cellulose succinate, metal flakes, n-alkyl dimethyl benzyl quaternary ammonium chloride, cetylpyridinium chloride, stearamidopropyl dimethyl-beta-hydroxyethyl ammonium nitrate, and N,N,N,N',N'-pentamethyl-N'-tallow trimethylene diammonium-bis (methyl sulfate). Such materials are used as antistatic and static dissipative agents that are formulated in coating compositions to protect from static buildup. Films and coats with static dissipative capabilities have surface resistivities in the range of 10.sup.6 to about 10.sup.9 ohm/sq.; those with antistatic capabilities have surface resistivities in the range of about 10.sup.9 to 10.sup.12 ohm/sq.
One purpose of the present invention is to provide a coating material that can be used to obtain a film coating having a surface resistivity below 10.sup.12 (in either the antistatic or static dissipative range), which at the same time is clear enough to be able to read printed detail through it. Another purpose is to provide coating compositions that are capable of providing films and coatings with surface resistivities in the preferred range of about 10.sup.9 to 10.sup.6. The most preferred films and coatings in this range will have these surface resistivities for both the low and high humidity levels. In all cases the films and coatings should be clear enough to read printed detail through it, but the most preferred compositions provided will be the most clear.